Houston Chronicle
By Michael Murney
Updated June 16, 2023 1:34 p.m.

Houston and the southeast Texas region are facing an extreme heat wave, with 113-plus degree heat index values and raw temperatures in the triple digits expected in the next several days, according to the National Weather Service.    

The NWS's forecast comes after ERCOT, the Texas power grid's governing body, predicted that the ongoing heat wave will drive the Lone Star State's total energy demand beyond its all-time record multiple times before the heat wave breaks. ERCOT issued a Weather Watch on Tuesday, urging Texans to track ERCOT's grid condition updates and plan to reduce energy use during high demand periods.

ERCOT provides a digital dashboard with real-time updates on grid conditions and changes in Texas' energy market with a wealth of information about the status of the grid. Here's Chron's guide to understanding the essential numbers and key terms the ERCOT dashboard has to offer.

How to read Grid Conditions

Among the first graphs visible on the ERCOT Dashboard is the "Grid Conditions" chart, which shows how much energy in megawatts (MW) the grid has in reserve when meeting the state's current energy demand. One MW is enough to power about 200 Texas homes when demand is high, according to ERCOT.

When operating reserves fall below 2,300 Megawatts (MW), ERCOT declares Energy Emergency Level 1. Under Level 1, Texans are at risk of experiencing short-term "controlled outages," and are encouraged to take steps to conserve energy use at home.  

Emergencies escalate from Level 1 up to Level 3, which ERCOT declares if the grid's energy reserves fall below 1,000 MW. At Level 3, ERCOT starts using "rotating outages," often referred to as rolling blackouts. "In extreme circumstances, more prolonged outages may be required to balance supply and demand on the electric system," ERCOT states on its website. 

"[Rolling blackouts] really are a tool of last resort," said Ed Hirs, an Economics Professor at the University of Houston specializing in energy markets. 

Hirs said the next important chart to look at on the dashboard is ERCOT's Supply and Demand chart. This chart displays a purple line representing how much energy the grid is capable of supplying in real-time, and a turquoise line showing current energy demand levels. 

"I look at [the Supply and Demand chart] all the time," Hirs said. "You begin to worry when you see those two lines start to converge." In other words, Texans should take note if the space between the grid's current capacity (in purple) and the state's current energy demand (in turquoise) starts to shrink, because the grid is close to maxing out its current capacity to keep Texans' heat and lights on, Hirs explained.